Персона:
Леонов, Александр Сергеевич

Организационные подразделения

Организационная единица

Институт общей профессиональной подготовки (ИОПП)

Миссией Института является: фундаментальная базовая подготовка студентов, необходимая для получения качественного образования на уровне требований международных стандартов; удовлетворение потребностей обучающихся в интеллектуальном, культурном, нравственном развитии и приобретении ими профессиональных знаний; формирование у студентов мотивации и умения учиться; профессиональная ориентация школьников и студентов в избранной области знаний, формирование способностей и навыков профессионального самоопределения и профессионального саморазвития. Основными целями и задачами Института являются: обеспечение высококачественной (фундаментальной) базовой подготовки студентов бакалавриата и специалитета; поддержка и развитие у студентов стремления к осознанному продолжению обучения в институтах (САЕ и др.) и на факультетах Университета; обеспечение преемственности образовательных программ общего среднего и высшего образования; обеспечение высокого качества довузовской подготовки учащихся Предуниверситария и школ-партнеров НИЯУ МИФИ за счет интеграции основного и дополнительного образования; учебно-методическое руководство общеобразовательными кафедрами Института, осуществляющими подготовку бакалавров и специалистов по социо-гуманитарным, общепрофессиональным и естественнонаучным дисциплинам, обеспечение единства требований к базовой подготовке студентов в рамках крупных научно-образовательных направлений (областей знаний).

Фамилия

Леонов

Имя

Александр Сергеевич

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Результаты поиска

Теперь показываю 1 - 10 из 33

Только метаданные
A New Algorithm for a Posteriori Error Estimation for Approximate Solutions of Linear Ill-Posed Problems
(2019) Leonov, A. S.; Леонов, Александр Сергеевич
A new algorithm for a posteriori estimation of the error in solutions to linear operator equations of the first kind in a Hilbert space is proposed and justified. The algorithm reduces the variational problem of a posteriori error estimation to two special problems of maximizing smooth functionals under smooth constraints. A finite-dimensional version of the algorithm is considered. The results of a numerical experiment concerning a posteriori error estimation for a typical inverse problem are presented. It is shown experimentally that the computation time required by the algorithm is less, on average, by a factor of 1.4 than in earlier proposed methods.
Только метаданные
Phase Modulations in a Speech Signal
(2022) Sorokin, V. N.; Leonov, A. S.; Леонов, Александр Сергеевич
© 2022, Pleiades Publishing, Ltd.Abstract: Mathematical models of the phase function and its parameters in speech-signal analysis problems have been investigated. The phase spectrum of a speech signal has been calculated using the Hilbert transform of signals at the output of a gammatone filterbank. Short- and long-term modulations of the linear phase component and phase derivatives with respect to frequency and time, and mixed derivative have been considered. The method for vowel segmentation using aggregation of the correlation coefficients of the phase parameters is described. Experiments on estimating the formant and pitch frequencies and the glottal opening and closure instants have been performed.
Только метаданные
Solution of the Inverse Elastography Problem in Three Dimensions for a Parametric Class with A Posteriori Error Estimation
(2019) Sharov, A. N.; Yagola, A. G.; Leonov, A. S.; Леонов, Александр Сергеевич
© 2019, Pleiades Publishing, Ltd.The paper presents the solution of a special three-dimensional inverse elastography problem: given a quasistatic model of a linear-elastic isotropic body subject to surface forces, to find the Young’s modulus distribution in the biological tissues under study using the known values of vertical displacements of these tissues. This study is aimed at detecting local inclusions in the tissue interpreted as tumors with values of the Young’s modulus that are significantly different from the known background. In addition, it is assumed that Young’s modulus is a constant function inside the unknown inclusions of a parametrically given geometry. This inverse problem leads to the solution of a nonlinear operator equation, which is reduced by a variational method to the extremum problem of finding the number of inclusions, parameters defining their shape, and the Young’s modulus for each inclusion. The problem is solved algorithmically by using a modification of the method of extending compacts by V. K. Ivanov and I. N. Dombrovskaya. To illustrate how the algorithm works, we give examples of solving model inverse problems with inclusions in the form of balls. A posteriori error estimation of the obtained distribution of Young’s modulus is carried out for the found solution to one of the model problems.
Только метаданные
Effective Algorithms for Computing Global and Local Posterior Error Estimates of Solutions to Linear Ill-Posed Problems
(2020) Leonov, A. S.; Леонов, Александр Сергеевич
© 2020, Allerton Press, Inc.We consider extremal problems introduced and investigated earlier by the author for calculating global and local a posteriori error estimates of approximate solutions to ill-posed inverse problems. For linear inverse problems in Hilbert spaces, they consist in maximization of quadratic functionals with two quadratic constraints. The article shows how under certain conditions these problems can be reduced to a problem of maximization of a special (written analytically) differentiable functional with one constraint. New algorithms for calculating global and local a posteriori error estimates based on the solution of these problems are proposed. Their effectiveness is illustrated by numerical experiments on a posteriori error estimation of solutions to the model two-dimensional inverse problem of potential continuation. Experiments show that the proposed algorithms give a posteriori error estimates close to the true error values. Proposed algorithms for global a posteriori error estimation turn out to be more rapid (3 to 5 times) than the previously known algorithms.
Только метаданные
Non-smooth regularization and fast gradient algorithm for micropore structure reconstruction of shale 页岩微米孔隙结构重构的非光滑正则化及快速梯度优化算法
(2020) Wang, Y.; Fan, S.; Lukyanenko, D. V.; Yagola, A. G.; Leonov, A. S.; Леонов, Александр Сергеевич
© 2020, Science Press. All right reserved.The understanding of shale microstructure is the basis of shale gas exploration and development. The traditional detection method is based on the surface damage observation method. In this work, the synchrotron radiation technology of Shanghai Light Source is applied to nondestructive detection of shale structure to obtain projection data, which can avoid X-ray hardening. We use X-ray Computed Tomography (CT) technology to restore images, and propose an L1 norm + TV (total variation) constrained non-smooth regularization method to suppress noise and improve image contrast. Experiments show that this method is effective to reconstruct the microstructure of shale accurately.
Только метаданные
Solution of the Two-Dimensional Inverse Problem of Quasistatic Elastography with the Help of the Small Parameter Method
(2022) Nefedov, N. N.; Sharov, A. N.; Yagola, A. G.; Leonov, A. S.; Леонов, Александр Сергеевич
© 2022, Pleiades Publishing, Ltd.Abstract: The direct and inverse problems of two-dimensional quasi-static elastography are considered within a tissue deformation model in which the tissue is treated as an elastic body exposed to surface compression. In the approximation of plane linear elastic deformations, the arising displacements of the tissue are described by a boundary value problem for partial differential equations with coefficients determined by Young’s modulus and the constant Poisson ratio of the tissue. This problem contains a small parameter, so it can be solved using the theory of regular perturbations of partial differential equations. The corresponding solution procedure is studied, and, under certain assumptions, simple formulas for solving both direct and inverse problems of two-dimensional quasi-static elastography are derived. Direct and inverse test problems are solved numerically with the help of the proposed formulas. The results agree rather well with the model solutions. The computations based on the formulas require fractions of microsecond on a moderate-performance personal computer for sufficiently fine grids, so the proposed small-parameter approach can be used in real-time cancer diagnosis.
Только метаданные
Restoration of the Oscillation Function for the Source Support in the Wave Equation
(2026) Bakushinskii, A. B.; Leonov, A. S.; Леонов, Александр Сергеевич
Только метаданные
A posteriori error estimates in linear ill-posed problems
(2026) Leonov, A. S.; Леонов, Александр Сергеевич
Только метаданные
Solving Some Inverse Problems of Gravimetry and Magnetometry Using an Algorithm That Improves Matrix Conditioning
(2024) Leonov, A. S.; Lukyanenko, D. V.; Yagola, A. G.; Леонов, Александр Сергеевич
Только метаданные
Phase Analysis of the Activity of a Voice Source
(2021) Sorokin, V. N.; Leonov, A. S.; Леонов, Александр Сергеевич
© 2021, Pleiades Publishing, Ltd.Mathematical models are proposed that make it possible to relate the parameters of a voice source with the parameters of the phase-frequency responses (PFR) of speech signal segments. In particular, it was found that the duration of operation of a source can be found from the average length of the intervals between the zeros and discontinuities of these PFR. For synthetic and real speech signals, based on the established properties of the phase response and the proposed heuristic methods for their analysis, a numerical estimate of the periods of the fundamental tone, the duration of the voice source within these periods, as well as the moments of the beginning Top and end Tcl actions of the voice source. The existence of the upper limit of the frequency range of the fundamental tone F0 within which the estimation error F0 does not exceed 5% is experimentally established. The average error in estimating the duration of a voice source using the proposed method for speech segments from the Arctic database was less than 0.3% for two speakers, and for a third speaker, it was 6.2%. It is shown that the error in determining values Top and Tcl depends on the properties of the voice source and increases significantly for F0 > 220 Hz. The most probable error in estimating quantities Top for three speakers from the Arctic database is estimated as 1.5, 10.2, and 13.5%; for Tcl, it is –9.7, –20.2, and –13.9%.